battery voltage

[spacerust]

i have a 12v battery installed. when i try to crank her up the voltage drops down to about 9 or 10v. Is this right? or do i need a new battery? would this effect and cause a hard start?

 

[JB]

Re: battery voltage

It is pretty normal for battery voltage to drop to 9-10 volts when the starter is engaged.

 

[Robj]

Re: battery voltage

What is the voltage at when the starter is not cranking. It should be over 12.5 v, if it is less than 12, then you battery is getting tired.

Have a great day,

Rob.

 

[dcg9381]

Re: battery voltage

I think Rob means not cranking AND running.

 

[joed]

Re: battery voltage

I think Rob means not cranking AND running.

Not cranking and running should be more like 13.5 votls.

 

[dcg9381]

Re: battery voltage

The value at the volt meter is subject to all sorts of parallel parasitic draw off of the other things that run on that battery - ignition for sure, probably lights - basically *anything* that's ON when the key is ON.
You'll have to learn the OK voltage for your electrical setup and gauge.

If you measure AT the battery, you'll get a much better reading. See how that compares to the gauge.

On my boat, running/charging, I see ~13V at the meter. Turn on the lights, which don't draw that much - but parallel off the same circuit, and I'll drop to 12.7 or so...

Measured at the battery, I see 12.2-12.7 (not charging)
12.9-13.7 charging/running.